PARDS--Beyond the Basics Part 2 with Dr. Nadir Yehya: Conventional Mechanical Ventilation
Jan 9, 2023
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Dr. Nadir Yehya, Assistant Professor of Anesthesiology and Critical Care and Pediatrics, discusses selecting initial PEEP and measuring variables for optimal PEEP. The chapter explores different strategies for setting PEEP in pediatric and adult patients. It also discusses the measurement of plateau pressure in pediatric mechanical ventilation and the use of esophageal pressure monitors to titrate ventilation support. Additionally, it explores how sedation levels can affect thoracic pressure in intubated patients.
The podcast discusses two different strategies for setting PEEP in intubated patients with ARDS: an escalating PEEP trial and a decelerating PEEP trial.
Plateau pressure is a commonly used metric for guiding ventilation strategies in ARDS, while the clinical significance of driving pressure, mechanical energy, and mechanical power as therapeutic targets remains uncertain.
Deep dives
Setting PEEP in Different Ways
In setting PEEP for intubated patients with ARDS, the podcast discusses two different strategies: an escalating PEEP trial and a decelerating PEEP trial. The escalating PEEP trial involves starting with an initial PEEP based on the patient's condition and adjusting it based on the inability to decrease FiO2 to 60% or less. The PEEP is gradually increased until oxygenation improves. On the other hand, the decelerating PEEP trial starts with a higher PEEP, recruits as much as possible, and then rapidly decreases the PEEP while assessing the improvement in oxygenation. These strategies are used depending on the patient's hemodynamic stability and the presence of recruitable lung. Both strategies have their advantages, including safety and potentially faster recruitment, but they require close monitoring of inspiratory and expiratory flows to ensure accurate pressure and volume delivery.
The Role of Plateau Pressure and Driving Pressure
Plateau pressure and driving pressure are commonly used metrics to assess lung protective ventilation in patients with ARDS. Plateau pressure, measured in volume control modes, is often used as a surrogate for stress and is important to keep below 30. Driving pressure, representing the difference between plateau pressure and PEEP, has also gained attention, but there is a lack of concrete evidence supporting it as a therapeutic target. Mechanical energy and mechanical power attempt to summarize the total energy delivered to the lung, but their clinical significance and value as therapeutic targets remain uncertain. Despite these challenges, plateau pressure continues to be a readily available and evidence-based metric for guiding ventilation strategies in ARDS.
Considering Thoracic Pressure in Ventilation Support
The podcast acknowledges the impact of thoracic pressure on ventilation support in patients with ARDS. Excessive abdominal competition or obesity can cause an increase in thoracic pressure, affecting the efficacy of set PEEP levels. While clinical use of esophageal pressure monitors is not common, their potential benefits in quantifying thoracic pressure and determining appropriate ventilation settings are recognized. However, the need for precise monitoring of thoracic pressure versus adjusting PEEP levels based on patient characteristics and clinical judgment remains a topic of discussion. The goal is to ensure optimal gas exchange while considering the challenges of intubated patients, including sedation levels and body habitus.
Implications of Ventilation Mode in ARDS
The podcast highlights the use of pressure control and PRVC (pressure regulated volume control) modes in ARDS patients. While volume control ventilation has been less commonly used in adult patients, it is more popular in pediatric settings. Institutions vary in their mode preferences, with a majority utilizing PRVC. There is ongoing debate over the most suitable mode and the impact of ventilation settings on lung damage. The discussion emphasizes the importance of lung protective ventilation strategies, considering factors such as plateau pressure, driving pressure, and mechanical power. However, the need for further research and clinical trials is emphasized to establish best practices and determine optimal ventilation settings.
Dr. Yehya is a graduate of the University of California at Berkeley and the University of California at Los Angeles School of Medicine. After completing pediatrics training at Children’s Hospital of Los Angeles, he completed his pediatric critical care fellowship at Children’s Hospital of Philadelphia (CHOP), and joined the faculty after graduation in 2011. He is currently an Assistant Professor of Anesthesiology and Critical Care and Pediatrics at the Perelman School of Medicine at the University of Pennsylvania and an attending physician in the pediatric intensive care unit at CHOP.
Dr. Yehya’s research interests encompass all aspects of pediatric respiratory failure, with a particular emphasis on pediatric acute respiratory syndrome (ARDS) and mechanical ventilation. ARDS consists of sudden, severe flooding of the lungs in response to an inflammatory insult causing difficulty breathing, frequently requiring mechanical ventilation. Sepsis is a leading cause of ARDS in children. His long-term goal is better characterization of ARDS in children and to test therapies designed to improve outcomes. His NIH-funded work is assessing the utility of specific plasma biomarkers in pediatric ARDS, with subsequent proteomic characterization and testing in pre-clinical models. Dr. Yehya has several active studies involving biomarkers, clinical epidemiology, and pathophysiological mechanisms in the field of pediatric ARDS, and is involved in several multicenter and multinational collaborations.
Objectives:
After listening to this episode, learners should be able to:
Understand the role of heated high-flow nasal cannula and non-invasive mechanical ventilation in the management of pediatric acute respiratory distress syndrome (PARDS).
Recognize the potential for patient self-inflicted lung injury in PARDS.
Recognize high-risk situations when non-invasive mechanical ventilation is relatively contraindicated in favor of intubation and mechanical ventilation.
Acknowledgement: Thank you to Dr. Nick Bartel for his help in creating learning objectives for this series.
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Thank you for listening to this episode of PedsCrit. Please remember that all content during this episode is intended for educational and entertainment purposes only. It should not be used as medical advice. The views expressed during this episode by hosts and our guests are their own and do not reflect the official position of their institutions. If you have any comments, suggestions, or feedback-you can email us at pedscritpodcast@gmail.com. Check out http://www.pedscrit.comfor detailed show notes. And visit @critpeds on twitter and @pedscrit on instagram for real time show updates.
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